Field of the Invention
The invention concerns a method to examine a tissue sample and a device to examine a tissue sample.
Description of the Prior Art
Examination of a tissue sample can be implemented after an extraction of the tissue sample from a living organism (biopsy).
In such a biopsy, for example, the tissue sample is extracted from the breast and is histologically examined. The extraction most often takes place with the aid of an imaging method. Stereotactic biopsy is an established examination method. For this purpose, the breast to be examined is compressed in a mammography apparatus between a support plate and a compression plate that can be displaced with respect to the support plate. A first x-ray image acquisition (scout image, 0° acquisition, overview acquisition) subsequently takes place with an x-ray source. Using this x-ray image acquisition a check is made as to whether the region to be examined is correctly positioned. For this purpose, an x-ray detector is typically integrated into the support plate.
The subsequent acquisitions typically take place in pairs from two different directions (what are known as stereo acquisitions). Given a stationary support plate, the x-ray source is moved in an angle range of +/−25° on a circular arc around the vertical axis. In the first two stereo acquisitions, the target (for example tumor or microcalcification) is marked, and from this the precise penetration position and penetration depth for the biopsy needle can be determined. The biopsy needle is subsequently introduced into the breast and the position of the biopsy needle is monitored by additional stereo acquisitions. In the case of a vacuum biopsy, the biopsy needle tip is located just before reaching the lesion and the needle is introduced into the relevant tissue with a firing mechanism that is a component of the biopsy unit. The tissue sample is removed by a lateral opening in the biopsy needle and—in the case of a vacuum biopsy—is transported into a sample container outside of the breast. In the case of microcalcifications, the sample is examined with the aid of an x-ray device in order to check the result of the biopsy. This can take place either at an extra x-ray system or at the biopsy system. However, for this purpose the breast must be uncompressed. An additional extraction of a sample under identical conditions with regard to the compression of the breast is thus not possible.
Examinations known as tomosynthesis examinations are often implemented with a mammography apparatus. For this purpose, a sequence of tomosynthesis projections is created, for example 25 projections, wherein the x-ray source (x-ray radiator) rotates over the detector in an angle range between −25° and +25°. The x-ray radiation is thus triggered at regular intervals of 2°, and a respective projection is read out from the x-ray detector. The three-dimensional subject is subsequently reconstructed from the projections in a tomosynthesis reconstruction process. The evaluation of the reconstruction result takes place in z-slices, i.e. in slices that are parallel to the x-ray detector.